The death of Mark Shand has been ruled an accident, according to a spokesmwoman for the medical examiner’s office in New York.
The animal conservationist and travel writer passed away on Wednesday aged 62, after he sustained injuries when he slipped and hit his head on the pavement outside an after-party for a charity event.
A spokeswoman for the examiner’s office said the death was caused by blunt impact head trauma with skull fracture and bleeding in the brain.
Mr Shand was in New York for an auction at Sotheby's in aid of a charity for underprivileged children and the Elephant Family, of which he was chairman, which aims to save the endangered Asian elephant from extinction in the wild.
Mr Shand's sister, the Duchess of Cornwall, and the Prince of Wales are believed to heard the bad news at their Birkhall home in Scotland.
“The Duchess, the Prince of Wales and all her family members are utterly devastated by this sudden and tragic loss,” a Clarence House spokesman said on Wednesday.
"Mark Shand was a man of extraordinary vitality, a tireless campaigner and conservationist whose incredible work through The Elephant Family and beyond remained his focus right up until his death."
Since his death was announced, tributes have poured in.
A spokesman for the Elephant Family described him as a "true force for conservation," "both a legend and inspiration and above all our great friend."
Dan Bucknell, head of conservation and campaigns at the charity, said Mr Shand had "infectious enthusiasm" for his work for Asian elephants.
He told the BBC: "He did so much for the charity, he was a very fun-loving, warm-hearted generous guy, who was always very hands-on with all the events that we did and we are going to miss him very sorely"
Mr Shand, Camilla's only brother, wrote numerous books and featured in documentaries, with elephants and India as recurring themes.
The adventurer's book Queen Of The Elephants won the 1996 Thomas Cook Travel Book Award and the Prix Litteraire d'Amis, and was made into a BBC documentary.
Additional reporting by PA